Telephotography.



0. D. KRUH. TEIEPHOTOGBAPHY.

Arrmonxol Imm roy. 1a, 1901.

Patented Allg. 23, 1910.

2 SHEETS-SHEET 1.

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3 n/um- W3-mlm Witnessesg,

.j o. o; KRUH.

TELBPHOTOGBAPHY. APPLOATIN FILED NOV. 19, 1907. Y

Patented Aug. 23, 1910.

2 SHEETS-SHEET 2.

Inventor: Oslas O Kr h hat] Fig. 5.

- --Aunmnnmv---q i To all whom 'it may concern,.- Be it known that I, OsIAs OTTO KRUH, a

' to the 1i tive. A seleniumcell is suitable for regu-v UNITED sTATEs PATENT oFF-Ion.

os'IAs or'ro kann, or scHENEcTAnY, NEW YORK, assreNo'rc 'ro' GENERAL ELE'cTa'rc COMPANY, A 'CORPORATION or' NEW' roma,

TELEPHOTOGRAPHY.

Specification ot Letters Patent;

Patented; Aug. 23,1910;

Application led November 19, 1907. Serial No. 402,787.

subject ofthe Emperorof Austria-Hungary, residing at Schenectad county of Schenectady, State of New York, have invented certain new and useful Improvements in Telephotography, ofwhich the following is a speeiication.

A complete telephotographic system ordinarilyQoomprises a sending station, a transmission line, and a receiving station. The

sending station is provided with meansl for projecting a' small ray of light through a photographic negative, with means on the other side lof the negative for varying or controllin an electric circuit in proportion gt transmitted through the negalating the electric current to correspond with variations in the light transmitted, when the spot of light is made to travel progressively over the surface of the nega-tive. The variations in current above mentioned act on a Suitable receiving ap aratus at the distant station and are use to reproduce, on a sensitizedy surface, the light and dark spots of the original ne ative. The reproductionv is a positive o the distant negative.

A system of the general type above-mentionedl is described by Korn in the Elektrotechnische Zez'tschrz'ft, Vol. 26, p. 1131, 1905.

My present invention comprises an improved receivin apparatus whereby the pulsations and uctuations of the line curl rent can be utilized to the best advantage lin the reproduction of the negative used at the y ical details whereby the spot of light is made sending end ofthe line.

The receiving apparatus hereinafter described is very simple in construction and operation and will record pictures with much greater rapidity than any other type of apparatus known to me.

In order to avoid confusion, and to simplify this application, I have confnedmy description largely to my own particular improvements, and have omitted the mechanto move rogresslvely overl the negative at 'the sendlng station, and whereby a synchronously voperating sensitive surface is moved-with respect-to the source of light at the receiving station.

lThe novel features of`my invention are particularly pointed out in the appended claims, for a better understanding of which,

slmple as possible.

reference is made to the following description taken in ,connection with the accompanying drawings.- These drawings have purposely been made diagrammatic and as 4 Figure 1 represents a complete system having a receiving apparatus comprising a catho eray tube; Fig. 2 is a broken perspective view of a special form of cathode- .ray tube; Fi 3 is amodiication of my in 65V,

vention in W ich a mercury vapor arc tube is used; Fig. 4 illustrates the use of a special type of mercury arc tube.

The general system illustrated in Fig. 1

comprlses a sending vstation having a selemum cell 1 receiving a ray of light 2 transmitted through a photographic negative 3 over which the spot is progressively moved.-

The variation in the intensity of the light falling on the selenium cell varies the resistance of the cell, in Aa well known manner, and thereby varies'the intensity of the current supplied by ay storage battery 4 and 'transmitted through a line conductor 5. At the receiving end of the line is anelec- 80 trornagnet 6 energized by the fluctuating current s ent out by the sending station.

Within the influence of this electromagnet .is'a cathode-ray tube 7 energized in any sultable manner as by means of a Tesla 85 transformer 8.

The cathode-ray tube is provided with an Opaque coverin over its entire surface eX- cept for a smal opening 9 through which' the rays are permitted to pass so that they 9o may act on a photographic plate. The cathode-ray tube is so located `with respect to the magnetic field that when the field is weak the luminous discharge through the tube is spread out through a wide area, and

gives, at the window 9, an illumination of' low intensity. If, however, the magnetic field is strongly increased as when the -'selenium cell l is greatly reduced in resistance by a strongdhght through the sending l negative, the lie acts to deflect the cathode rays and concentrate them in apathpassing directly before the window 9. This increases the intensity of the light projected upon the photographic' thereon-a highly expose spot or trace corresponding to the spot or traces on the sending negative.

To intensify the concentrating action of the -electromagnet 6I prefer 'to make the 110 Cplate and produces cathode ray tubegof the special type illustrated in Fig. 2. The tube is" semlcircular alon the back 10 but is wedge-shaped on the ront and'has the transparent window 9 at the apexof this wedge. The result is that when the magnetic eld is shifted over toward the window.v it is also contracted sidewise to give a high luminous intensity immediately back of the window.

It should be noted that the system just described is entirely free from anymovin parts and is thus well adapted to respon quickly to changes in the current `transmitted` over the l1ne conductor. In this respect it is far superior to systems using mov-l able coils and contacts, the inertia of which is so great that a photograph cannot `be transmltted in less than about 'three to'ten mmutes.

In the modification shown diagrammatic-l ally inl Fig. 3, the light givingy source of the receiving station consists of a mercury arcl lamp 11 energized by a' storage battery or other source of directcurrent. This lamp, like the cathode ray tube illustrated in Fig. '1, has an opaque coating and a transparent window 12 andA is Wedge-shaped in crosssection to facilitate the concentration of the/ arc immediately back of the transplarent window 12. The o eration is essentia ythe same as thatrecite in connection with Fig. 1. -I nd that when a mercury arc device is used, the magnetic field produced by electromagnetsy 13 andv '14 must be relatively strong to secure the desired fluctuation in the intensity of the light at the window.y When the electromagnets are stron they nec essarily oder some considerab e inductance and thus tend somewhat to limit the speed at which pictures can be transmitted. The modification illustrated in Fig. 4 is not subject to this disadvantage. The tube has the characteristic of extreme sensitiveness; contively weak; it wil then oerlittle impedance to the fluctuating current of the line.

In Fig. 4 the mercury vapor apparatus 15 is provided with a hollow anode 16. .I nd that when such an apparatus is runnin under normal conditions there may be foun inclosed within the hollow anode a sort of halo or flame diering essentially from the main body of. the arc. I have found that when such an apparatus is iroperly located in a magnetic e d, this ha o or tongue of ,flame protrudes from. the hollow anode' to p 45sequently the magnetic field can be relaan extent about proportional to the strength one side of the end of the hollow anode 16 and in'such position that the magnetic field established by electromagnets 18l and 19 will cause the halo to be thrust out of the hollow anode and then deflected sidewise until it is v progressively immediateel baci: of the window. revi-l ously stat this movement of the ha o can be effected with a very weak magnetic field; consequently the electromagnets 18 and 19 ma have but a few turns and will oer litt e impedanpe to the line current of the v system. he halo above mentionedis particularly sensitive when the mercury arc is running at a low current, or when the mercury va or is at low pressure.

vIt wi be clearly understood that inthe several types of ap aratus above described the illumination ofp the window will vary from bright to dark in about the roportion of the current 4variations in' the ine', that is, with high current the concentration of the light atf'tliewindow will be at a maximum, whereaswith .but a moderate current the illumination will be lower and will give what may be called a half-tone exposure to a part vof the receiying photographic plate.

W at I claim as new and desire to secure by Letters Patent of the United States, is,-

1. In a telephotographic system, a lumi- 99 Y nous tube. having a light transmitting window, and electromagnetic means for varying the intensity of light at said window to cor,- respond with the variations in current received from al distant point. 2. In a system of telephotography, areceiving apparatus comprlsingan evacuated envelop maintained luminous b electrical.v ener said envelop having a -ght trans mittlng window, and 4means for controlling' the distribution of current through said envelop to control the illumination at said window ina manner to correspond with the variations in current transmitted to said re-v ceiving apparatus from-a distant station.

j 3. The combination of an evacuated envelop having opaque walls and a light transmittingl window, means for assin current throug said envelop to ren i er it uminous and magnetic means for shifting the vpath ot current in said envelop to vary the intensity 'of light at said window. J v

4. The combination of a source of'light inclosed in an opaque envelop havin alight' transmitting window, a source of e ectrical energy for maintaining said source of li ht, and electromagnetic means for ycontrol mg the distribution of current within said envelop to vary the intensity of the light transmitted through saidwindow.

5. The combination of an evacuated envelop having aA substantially wedge-shaped f cross-section, an opaque coating therefor-f having a light transmitting window near the apex of the wedge, meansv for passing 125 current throu h said tube, and ma etic means for shiting the distribution o said current to vary the intensity of light transmitted through said window. v v

`6. In a system of telephotography, the 130 besas;

combination of a mercury vapor-'lamp havmg an opaque covering with a lighttfransl mitting window, an anode for `said mercury with respect to said 4light transmitting wincombination of means for estab mmous electrlcal dischar e5 means for 1sodow. l l

7. In a system of vtele hoto hy the p ,a ln-v lating a beam of light pro uced thereby, and electromagnetic vmeans acting` vdirectly upon the discharge so as to produce successive variations of actinic intensity in said beams 8,.- The -combination -of a source of electrical energy, a vapor electricrdevce, com- :prising a suitable envelo source, means for establishing a beam of f ight from .said device in a given direction, an, electromagnetic means for varyingy the connected to said intensity of said beam in 'such'manner as 4 .to produce a' succession of varyingimpresy sions upon avphotogra hic surface.

In Witness whereo I have hereunto set my hand this 18th Vday of November, 19(27.

osIAs-o'mo Witnesses: i i

BENJAMIN B. HLn, HELEN Oumma. 

